Such grippers exist, for example, for intervertebral disk punches, for arthroscoping forceps, for operations in the knee-joint region, for rhinology, for stomach and intestinal surgery. These grippers are used for the actuation of rod-like attachments which are in the range of 1 decimeter or more. The attachments are sometimes interchangeable. At their free end, they bear the actual punching tool, cutting tool or the like.
The attachment has to be inserted through an opening into the inner body. Where there is an opening in the body, it should not be injured during either introduction or withdrawal of the attachment. Injury could arise if, for example, a scissor component, a punch component, a forcep component or the like projects beyond the outline of the attachment.
Up until now, the practice in using such tools has been that the double levers are pushed together by the operating surgeon's hand. In this position, nothing, or very little, projects beyond the outline of the attachment and thus the attachment can be introduced into the opening. Once the tool is in the desired position, it is brought into its initial position by releasing (fully or partially) the arms by the force of the spring action and then cutting, punching or gripping or the like is carried out by renewed pressing together of the arms, overcoming the force of the spring device. When the attachment is withdrawn from the opening, the arms are again pushed together.
This configuration has disadvantages in handling: when introducing the attachment, it is possible that the arms have not been brought completely into closed position and do indeed project a little beyond the outline of the attachment. The same applies in withdrawal of the attachment. It must be imagined here that this introduction and withdrawal could be performed very frequently, for example to take out parts punched-off. If both the arms of the gripper have to be pressed together, namely against the force of the spring device, and the attachment has to be introduced, this makes twin demands both on concentration and on force.